1. Field of the Invention
The present invention relates to a recorded information reproducing apparatus for reproducing recorded information from a recording medium.
2. Description of the Related Art
In order to read recorded information with high accuracy from a recording medium on which information is recorded with high density, it is necessary to eliminate the influence of crosstalk from a track or tracks adjacent to a track that is being read.
In order to eliminate the crosstalk, first, the recorded information is read from the track that is to be read (hereinafter, referred to as “main track”) as well as from the track or the tracks adjacent to one side or both sides of the main track (hereinafter, referred to as “sub track”) simultaneously, and respective read signals are obtained. Next, in accordance with a level correlation between the read signal read from the main track (hereinafter, referred to as “main read signal”) and the read signal read from the sub track (hereinafter, referred to as “sub read signal”), a crosstalk component from the adjacent track is detected. Then, a read signal, from which the crosstalk has been eliminated, is obtained by subtracting this crosstalk component from the main read signal.
Here, if the recording medium that is to be reproduced is, for example, a writable disc such as a CD-R, CD-RW, DVD-R, or DVD-RW, a recorded area in which information data are written and an unrecorded area may coexist on the disc. Thus, when a pickup is tracing the outermost circumference (or innermost circumference) in the recorded area, a sub track may be located in the unrecorded area. In this case, no information data are recorded in the sub track, so that a correlation between the main read signal read from the main track and the sub read signal read from the sub track cannot be detected. Further, if no information data are recorded in the sub track, due to the influence of a tiny main read signal component leaked into the sub read signal, the correlation between the main read signal and the sub read signal becomes high. That is to say, an autocorrelation is performed due to the leakage from the main track into the sub track, so that a high correlation is detected despite the fact that this is not a situation in which the correlation is high. Therefore, there has been the problem that crosstalk is eliminated erroneously due to the crosstalk detection affected by this autocorrelation.